s57-parser

Live Demo — parse a real NOAA chart in the browser. No server, no GDAL.

Pure TypeScript parser for S-57 and S-101 marine navigational charts with S-52 symbology rendering in the browser.

Zero runtime dependencies. Works in Node.js, Bun, and browsers. 127 tests.

Packages

Package	Description
@s57-parser/iso8211	ISO 8211 binary format parser
@s57-parser/s57	S-57 ENC data model, topology, GeoJSON conversion
@s57-parser/s101	S-101 ENC parser (S-100 framework), auto-detection
@s57-parser/s52-render	S-52 Canvas2D renderer (IHO symbology, 3 palettes)
@s57-parser/leaflet	Leaflet plugin with S-52 canvas overlay
@s57-parser/maplibre	MapLibre GL JS plugin (GeoJSON source + canvas layer)
@s57-parser/cli	CLI tool: parse and inspect S-57/S-101 files

Quick Start

npm install @s57-parser/s57 @s57-parser/s52-render

Parse an S-57 chart

import { parseS57, toGeoJSON } from '@s57-parser/s57';

const response = await fetch('/chart/US5MA19M.000');
const buffer = await response.arrayBuffer();

const dataset = parseS57(buffer);
const geojson = toGeoJSON(dataset);

console.log(`${dataset.features.length} features`);
console.log(`${dataset.spatialRecords.size} spatial records`);

Render with S-52 symbology

import { parseS57, toGeoJSON } from '@s57-parser/s57';
import { renderChart } from '@s57-parser/s52-render';

const dataset = parseS57(buffer);
const geojson = toGeoJSON(dataset);

// Attach attributes for conditional symbology (depth-based coloring, etc.)
for (const f of geojson.features) {
  const feat = dataset.features.find(d => d.rcid === f.properties.RCID);
  if (feat) f.properties._attributes = feat.attributes;
}

const canvas = document.getElementById('chart') as HTMLCanvasElement;
const ctx = canvas.getContext('2d')!;

renderChart(ctx, geojson, {
  toPixelX: lon => /* your lon-to-pixel transform */,
  toPixelY: lat => /* your lat-to-pixel transform */,
}, canvas.width, canvas.height, { mode: 'DAY_BRIGHT' });

S-101 support

import { parseS101, isS101, toGeoJSON } from '@s57-parser/s101';

// Auto-detect format
if (isS101(buffer)) {
  const dataset = parseS101(buffer);
  const geojson = toGeoJSON(dataset);
  // GeoJSON properties include OBJL mapped to S-57 codes
  // for compatibility with the S-52 renderer
}

Leaflet integration

import L from 'leaflet';
import { S57Layer } from '@s57-parser/leaflet';

const map = L.map('map').setView([42.35, -70.88], 12);
L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png').addTo(map);

const response = await fetch('/chart/US5MA19M.000');
const buffer = await response.arrayBuffer();
const layer = new S57Layer(buffer, { mode: 'DAY_BRIGHT' });
layer.addTo(map);

// Cycle display modes
layer.setMode('DUSK');
layer.setMode('NIGHT');

MapLibre GL JS integration

import maplibregl from 'maplibre-gl';
import { addChartSource } from '@s57-parser/maplibre';

const map = new maplibregl.Map({ container: 'map', style: '...' });

const response = await fetch('/chart/US5MA19M.000');
const buffer = await response.arrayBuffer();

// Option 1: Native vector rendering with S-52-inspired styles
addChartSource(map, buffer, { sourceId: 'enc' });

// Option 2: Full S-52 canvas overlay
import { S57CanvasLayer } from '@s57-parser/maplibre';
const layer = new S57CanvasLayer('enc-overlay', buffer);
map.addLayer(layer);

Typed feature access

import { parseS57, typedFeatures, filterByClass } from '@s57-parser/s57';
import type { Light, DepthArea } from '@s57-parser/s57';

const dataset = parseS57(buffer);
const typed = typedFeatures(dataset.features);

// Filter by object class with full type narrowing
const lights = filterByClass(typed, 'LIGHTS');
for (const light of lights) {
  // light is Light — litchr, sigper, sectr1, sectr2 are typed
  console.log(`${light.name}: ${light.litchr} period=${light.sigper}s`);
}

const depths = filterByClass(typed, 'DEPARE');
for (const area of depths) {
  // area is DepthArea — drval1, drval2 are typed numbers
  console.log(`Depth: ${area.drval1}–${area.drval2}m`);
}

15 object classes supported: DEPARE, DEPCNT, SOUNDG, COALNE, LNDARE, LIGHTS, BCNCAR, BCNLAT, BOYCAR, BOYLAT, BOYSAW, BOYSPP, OBSTRN, WRECKS, UWTROC, RESARE, BRIDGE, LNDMRK, ACHARE.

Apply incremental updates

import { parseS57 } from '@s57-parser/s57';
import { applyUpdate } from '@s57-parser/s57';

const base = parseS57(baseBuffer);    // .000 file
applyUpdate(base, update001Buffer);   // .001 file (mutates dataset)
applyUpdate(base, update002Buffer);   // .002 file

Features

ISO 8211 Parser

• Full ISO/IEC 8211 binary format support
• Variable-length fields, mixed binary/text encoding
• Both b15 (suffix) and B(40) (parenthesized) binary field notations

S-57 Parser

• Typed feature API: 15 object classes with parsed attributes (DepthArea, Light, Buoy, etc.)
• Attribute catalogue with IHO standard ATTL codes
• Feature and spatial record extraction
• Chain-node topology resolution (VRPT edge endpoints)
• Coordinate scaling (COMF/SOMF)
• GeoJSON conversion (Point, MultiPoint, LineString, Polygon)
• Update mechanism (.001/.002 incremental files)

S-101 Parser

• S-100 framework ISO 8211 encoding
• 160+ feature types with full catalogue
• Complex (nested) attributes
• Information records and associations
• S-57 OBJL mapping for renderer compatibility
• Auto-detection (isS101)

S-52 Renderer

• Three IHO display palettes: DAY_BRIGHT, DUSK, NIGHT
• 50+ object class symbology rules
• Conditional symbology: depth-dependent DEPARE coloring, light color by COLOUR attribute
• Text labels: sounding depths, depth contour values, light characteristics (IHO abbreviations)
• Sector lights: arc rendering with bearing-based sectors
• Pattern fills: hatch, cross-hatch, stipple
• Priority-based rendering (8 display priority levels)

S-52 Display Modes

Mode	Use case
DAY_BRIGHT	Full daylight, highest contrast
DUSK	Twilight, reduced brightness
NIGHT	Night vision, dark red-tinted

Architecture

@s57-parser/iso8211       Pure ISO 8211 binary parser
       |
  +---------+
  |         |
@s57-parser/s57    @s57-parser/s101
  |         |
  +---------+
       |
@s57-parser/s52-render    Canvas2D S-52 renderer
       |
  +---------+
  |         |
@s57-parser/leaflet    @s57-parser/maplibre

Test Data

Download free NOAA ENC charts from charts.noaa.gov (S-57 .000 files, ~782 MB total).

Place files in the test-data/ directory for integration tests.

Development

# Install dependencies
bun install

# Run all tests (127 tests across 8 packages)
bun test

# Build all packages
bun run build

# Run demo viewer
bun run demo/serve.ts

Contributing

Contributions welcome. Areas that need help:

• WebGL renderer for large charts (millions of coordinates)
• S-63 encryption/decryption support
• Additional S-101 test data validation
• Performance optimization for mobile browsers

Author

Built by Vladislav Popov — vladislavpopov.ru · GitHub @devladpopov

Questions, integration help, or commercial/consulting inquiries: open an issue or reach me at vlad@alumni.york.ac.uk.

License

MIT © Vladislav Popov